Fuel injection pump for internal combustion engines having a plurality of combustion chambers

ABSTRACT

A FUEL INJECTION PUMP FOR INTERNAL COMBUSTION ENGINES, IN WHICH A RECIPROCABLE PUSHROD HAS ROTATABLY ADJUSTABLY MOUNTED THEREIN A PRISMATIC SHAFT WITH A PLURALITY OF SUBSTANTIALLY PLANE SIDES DIFFERENTLY SPACED FROM THE AXIS OF ROTATION OF SAID PRISMATIC SHAFT MEANS, SAID PRISMATIC   SHAFT MEANS HAVING ITS AXIS OF ROTATION EXTENDING SUBSTANTIALLY PERPENDICULARLY WITH REGARD TO THE RECIPROCATORY MOVEMENT OF THE INJECTION PLUNGER RESTING ON ANY SELECTED SUBSTANTIALY PLANE SIDE OF SAID PRISMATIC SHAFT MEANS.

Jan. 5, 1971 J. BERG 3,552,219 v FUEL INJECTIOi- PUMP FOR INTERNAL COMBUSTIONENGINES HAVING A PLURALITY OF COMBUSTION CHAMBERS Filed April 18, 1969 /n van for:

United States Patent 3,552,219 FUEL INJECTION PUMP FOR INTERNAL 'COM- BUSTION ENGINES HAVING A PLURALITY OF COMBUSTION CHAMBERS Josef Berg, Cologne-Kalk, Germany, assignor to Klockner-Humboldt-Deutz Aktiengesellschaft, Cologne- Deutz, Germany Filed Apr. 18, 1969, Ser. No. 817,414 Claims priority, application Germany, Apr. 27, 1968, 1,751,477 Int. Cl. F16h 25/08, 53/06; F04b 49/00 U.S. CI. 74-55 4 Claims ABSTRACT OF THE DISCLOSURE A fuel injection pump for internal combustion engines, in which a reciprocable pushrod hasrotatably adjustably mounted therein a prismatic shaft with a plurality of substantially plane sides differently spaced from the axis of rotation of said prismatic shaft means, said prismatic shaft means having its axis of rotation extending substantially perpendicularly with regard to the reciprocatory movement of the injection plunger resting on any selected substantialy plane side of said prismatic shaft means.

The present invention relates to a fuel injection pump for internal combustion engines with a plurality of combustion chambers in which each combustion chamber has associated therewith a pump piston driven 'by a cam through the intervention of a pushrod, said pump piston being axially adjustable in its basic position for adapting the position of the piston to the ignition pressures.

With multicylinder medium and large diesel internal combustion engines, it is customary to equalize the ignition pressures of the individual cylinders. This is brought about by displacing the start of the ignition either by correspondingly rotatably adjusting the pump cam or by changing the idling stroke up to the closing of the suction bore when pumps without suction valves are employed. Thechange in the idling stroke is eifected by changing the length of the pushrod between the pump piston and the cam and, more specifically, either by turning up or turning down the adjusting screw located between the pushrod and the pump piston or by exchanging shims of diflierent thicknesses. 'Both of these steps have the drawback that they require large access openings for permitting an adjustment. These openings have to be closed by a cover. Additional difiiculties are encountered when employing an adjusting screw inasmuch as such screw has necessarily to be secured in its respective position.

It is, therefore, an object of the present invention to provide a fuel injection pump for internal combusion engines with a plurality of combustion chambers, which by the employment of simple means will permit a change in the idling strike of the pump piston while requiring a small opening only in the pump housing.

It is another object of this invention to provide a fuel injection pump as set forth in the preceding paragraph, which will permit a change in the idling stroke of the pump piston also while the internal combustion engine is in operation.

These and other objects and advantages of the invention will appear more clearly from the following specification in connection with the accompanying drawing, in which:

FIG. 1 is a cross section through a fuel injection pump according to the invention.

FIG. 2 is a cross section through a portion of the .arrangement of FIG. 1, said section being taken along the line 11-11 of FIG. 1.

FIG. 3 is a sectional view similar to FIG 2, but showing a cam with a spiral contour.

The fuel injection pump according to the present invention is characterized primarily by a prismatic shaft which is rotatably arranged in the pushrod so as to be able to rotate in a direction transverse to the direction of movement of said pushrod, the sides of said prismatic shaft being differently spaced from the axis of rotation of said prismatic shaft while serving to support the pump piston.

By rotating the prismatic shaft, a stepwise change in the length of the pushrod between pump piston and the cam is obtained. This brings about a corresponding change in the idling stroke of the pump piston and displacement of the start of the ignition. In this connection it is advantageous that the respective plane side of the prismatic shaft which serves for supporting the pump piston engages the plane end face of the pump piston and thus will during the rotation of the pump piston be secured against an accidental rotation without necessitating additional means.

The fine degree of adjustment is determined by the number of sides of the prismatic shaft. In this connection it is advantageous so to select the difierence in the distance between the sides of the prismatic shaft and the axis of rotation of said prismatic shaft that a uniform ignition pressure adjustment will be obtained, It is furthermore advantageous so to design the prismatic shaft that the points of sides of the prismatic shaft which are closest to the axis of rotation of the latter are located on a spiral. A rotation of the prismatic shaft in one direction will then yield a uniform increase in the ignition pressure, Whereas a rotation in the opposite direction will uniformly decrease the ignition pressure.

According to a further development of the invention, both ends of the prismatic shaft have circular cylindrical bearing flanges which on all sides radially protrude beyond the circumference of the prismatic shaft. Such an arrangement greatly facilitates the production and assembly.

For purposes of simplifying the adjustment, it is suggested, according to a further development of the in vention, within the region of the prismatic shaft and axis parallel thereto to provide a hollow bolt in the pump housing which bolt is adapted, when the pushrod occupies its upper position, to move into a recess provided in said pushrod and through which, in engaged position, it will be possible to acuate a device for rotating the prismatic shaft.

Referring now to the drawing in detail, the arrangement shown therein comprises a pump piston 1 which is adapted to be driven by a cam 2 through the intervention of a pushrod 3. The pushrod 3 has associated therewith a wheel 4 which is adapted to roll on the circumference of. the cam 2. Arranged in the pushrod 3 is a prismatic shaft 5 with circular cylindrical bearing flanges 6, said shaft 5 being rotatable about an axis extending transverse to the direction of movement of said pushrod 3. The end face 7 of the pump piston 1 rests on one of the sides 12 of said prismatic shaft 5 while a spring 8 continously urges the end face 7 into and maintains the same in operative engagement with the respective side 12 of shaft 5 and through the latter maintains roller or wheel 4 of pushrod 3 in engagement with cam 2. More specifically, the spring 8 acts upon a collar 9 of the pump piston 1 and on the other hand rests on a guiding member 10 in the pump housing 11. The prismatic shaft 5 has six sides 12 which are differently spaced from the axis of rotation 13. These differences are so selected that when the prismatic shaft is rotated, a uniform adjustment of the ignition pressure is obtained. On the other hand, those points of the sides 12 which are closest to the axis of 3 rotation 13 are located on a spiral not shown in the drawing.

Within the region of the prismatic shaft 5 there is provided a hollow bolt 14 which is located in the pump housing in axis parallel relationship to shaft 5. This bolt 14 is adapted in the upper position of the pushrod 3 to move with its end 15 into a recess 16 after bolt 14 has been rotated by 180 from the position shown in FIG. 1. In this position, the said bolt 14 is held by a spring 17. When the bolt 14'is retracted against the thrust of spring 17 and is turned back to its FIG. 1 position, its stud 18 rests against a collar 19 of a connecting flange 20. The bore 21 of the hollow bolt 14 is closed by a stopper 22. When an adjustment is to be effected, the hollow bolt 14 is moved into engagement with recess 16 and by means of a Wrench (not shown) introduced through bore 21 into a corresponding recess 23 in the end face of the prismatic shaft 5, shaft 5 is turned and brought into the desired position.

Within the region of the free end face 27 of piston 1 there is provided a suction bore 24, and after the pump piston 1 has moved over the latter, the injection starts. The shorter the stroke, which can be changed by turning the prismatic shaft 5, between the free end face 27 of pump piston 1 and the upper edge 28 of the inlet bore 24 in the basic position of the piston, the earlier the injection will start.

The fuel is during the injection by means of a pressure valve 25 and a pressure bore 26 pressed into the fuel pressure line (not shown in the drawing).

It is, of course, to be understood that the present invention is, by no means, limited to the particular structure shown in the drawing but also comprises any modifications within the scope of the appended claims. It is furthermore to be noted that the present invention is advantageous not only with internal combustion engines having a plurality of cylinders with a corresponding number of reciprocable pistons, but is also highly advantageous with all other internal combustion engines having a plurality of combustion chambers, as for instance rotary piston internal combustion machines, in which an adaptation of the ignition pressures is required.

What I claim is:

1. A fuel injection pump for internal combustion engines, which includes: reciprocable fuel injection plunger means, reciprocable hollow pushrod means operable to convey actuating pressure to said plunger means, cam shaft means operable to actuate said pushrod means, rotatable prismatic shaft means located within said pushrod means and having its axis of rotation extending transverse to the direction of reciprocation of said pushrod means, said prismatic shaft means having a plurality of substantially plane areas forming a plurality of sides respectively differently spaced from the axis of rotation of said shaft means, each of said sides being adapted selectively in conformity with the rotational setting of said shaft means to be moved underneath said plunger means for supporting the same.

2. A pump according to claim 1, in which the vertical projection of those points of said sides of said prismatic shaft which have the shortest distance from the axis of rotation of said shaft has the said points located along a spiral, and in which said points are successively spaced from said axis of rotation in such a way that a uniform ignition pressure adjustment is obtained when said plunger means is successively supported by said sides of said prismatic shaft means.

3. A pump according to claim 1, in which both ends of said prismatic shaft means are provided with cylindrical bearing flanges radially protruding beyond the substantially plane sides of said prismatic shaft means and rotatably journalled in said pushrod means.

4. A pump according to claim 1, which includes hollow bolt means extending substantially parallel to the axis of rotation of said prismatic shaft means and being located within the region of reciprocatory movement of said prismatic shaft means within said pushrod means, said hollow bolt means being adapted in one end position of said pushrod means to be substantially axially aligned with said prismatic shaft means to permit the insertion of a tool through said hollow bolt means for turning said prismatic shaft means to set the desired substantially plane side thereof for engagement with said plunger means.

References Cited UNITED STATES PATENTS 287,697 10/1883 Marchanol 103-38 716,156 12/1902 Whalen 74-55 1,372,408 3/1921 Dyson 74-569 1,612,031 12/1926 Lanzerotti-Spina 74-569 1,798,378 3/1931 Kott 74-55 2,478,500 8/1949 Parsons 103-38 2,567,735 9/1951 Scott 74-569 FOREIGN PATENTS 334,619 10/1903 France 74-55 HENRY F. RADUAZO, Assistant Examiner US. Cl. X.R. 

